Brines Acoustics

Single Driver Speaker Systems

12/26/14 It is time to revisit most of the narrative on this site. Most of
it was written over 10 years ago and some, if not the majority of this
information is becomming seriously dated. As a start, I deleted the entire
theory section. Since I wrote those sections, practical knowlege of
transmission line type speakers has matured substantially. I will make comments
on design procedures eslewhere as I rewrite the site.

I will now remove the Facebook link. As with the previous forum, no one
contacts me via forum or Facebook, only via email. OK, so be it. The only way
to contact me is via the email link below. Feel free to contact be at any
time.

Single-driver speakers are not for everyone. Single-driver speakers are
about finesse, not power. Any speaker, single-driver, 2-way, 3-way, whatever,
is a compromise. Each will have sonic advantages and failings. Therefore, you
will wind up choosing speakers that work well with the bulk of your library and
OK with the rest. There just isn't a speaker out there that plays everything
well.

Again, single-driver speakers are about finesse. They provide a special
purity of tone without the phasing problems inherent with multi-way
cross-overs. The human ear is particularly sensitive to phase in the 300-3000Hz
band. This is how we locate sounds in space. While the combined phase of a
multi-way speaker may sum flat, we can still hear the phase rotation of each
driver as it enters the cross-over range. This phase rotation confuses the ear,
causing a lack of definition to the sound. A single-driver speaker obviously
doesn't have this problem and the mid-range of a single-driver speaker is
unexcelled.

But, of course, there is a trade-off. The nemesis of single-driver speakers
is frequency modulation (FM) of the upper ranges by the bass. (Doppler
distortion is a type of FM distortion, not the other way around.) A higher
frequency becomes a warble tone, the frequency and depth of the warble
depending on the frequency and driver displacement of the bass tone. The result
is when there are many bass frequencies in the music, as the music becomes loud
(more driver excursion) the upper ranges become harsh and tonally indistinct.
The driver "falls apart".

How bad is the FM distortion on a single-driver speaker? It depends! Music
with simple bass lines never sound better than on a single-driver speaker. Jazz
trio, girl-and-a guitar, classical chamber music. If you listen to your music a
moderate levels -- ~70dB and the listening chair 6-8feet from the speakers, you
can play almost anything. Music to avoid: Hard rock, most anything mastered
this century for radio and ear-buds, romantic symphonies at concert levels.

So you have been warned. If you are into polite genre and moderate levels,
my speakers are for you. If you are into heavy, loud music, you need to look
elsewhere.

Single driver speakers have a unique sound. That sound comes from a lack of
a conventional crossover. In a two-way speaker, the acoustic phase of each
driver rotates in opposite directions around the crossover point. While the
combined phase may be correct at the crossover point, away from that point, the
phase will be constantly changing. Why is this important? The human ear/brain
is designed to locate sounds primarily by phase. We are very sensitive to phase
in the 300-3000Hz range. Outside on this range, sound location becomes
increasingly difficult, but within this range, if the phasing is messed up, the
sound stage lacks precision and depth. A normal two-way speaker has the
crossover point in the middle of 1500-2000Hz range, which is smack in the
middle of the frequency band where humans are most sensitive to phase changes.
By not having a crossover and the attendant phase problems, a single driver
speaker sounds much more natural.

A good single driver speaker is more articulate and detailed in the bass and
midrange that a multi-way speaker. Because the driver in a single driver
speaker must work up to 10kHz and beyond, the cone is much lighter than the
cone of a comparably sized driver in a multi-way speaker that is crossed out by
2kHz. Less cone mass means faster response to the electrical signal and better
transient response. The lighter cones also promote higher efficiency. While my
speakers don't qualify as "high-efficiency", all of my speakers are in the high
80's and low 90's, making them good matches to all but the smallest tube
amplifiers. I suggest moderate powered class-D amps, and they work great with
high-powered solid-state amplifiers too.)

Why Quarter Wave Pipes?

You can't fool Mother Nature. ANY tall, thin ported speaker is a
quarter-wave resonator. Ever since the beginnings of hi-fi, designers have been
building floor-standing speakers with ports thinking that they were designing
bass reflex speakers and then scratching their heads trying to figure out why
they were getting spiky bass response. The answer is simple. The dominant
resonance is not cavity (Helmholtz) resonance but quarter-wave standing waves.
Understanding this, it is relatively easy to get a smooth bass output without
peaks or boominess.

Using the full potential of quarter-wave resonance, it is possible to get
seemingly impossibly low bass with relatively small drivers. The 6" and 8"
drivers I use can easily produce bass notes below 40Hz. This means that for
acoustic music and electronic music based on a 4-string bass guitar, no
subwoofer is necessary. Of course, for 5- or 6-string bass guitars or serious
organ music, a sub will help a lot.

What do I have to offer?

I specialize in speakers that use the Mark Audio drivers, with a smattering
of Lowther,Tang Band and Fostex drivers. I offer ready to play speakers in
furniture grade cabinets. These speakers will be custom built to your
specifications. You pick the veneer species and the stain that will go best
with your decor. While most customers select the oak or mahogany veneer, I will
use anything that I can get. You will be asked to pay my cost difference
between the "standard" veneer and your chosen premium veneer. The same policy
applies to the electrical components. I use the standard offering of Parts
Express or Madisound, but I will install any premium parts you request for only
the cost difference of the parts.

For the DIY'er, I offer plans for all of my commercial speakers. I offer
flat packs for those who cannot cut up a sheet of plywood on their own. I do
not offer assembled, unfinished cabinets.

I will alway answer general questions about speakers through e-mail. If you seek specific design
information about your project or would like me to design and/or built a pair
of speakers for your specific needs, I will negotiate a price for services with
you.

Pricing and Payment

My pricing is unusually low for the quality of the parts and construction I
use. This is primarily due to the small size of my operation. I have very
little overhead. My shop is part of my house, and I make no effort to recover
any part of that cost either by adding it to the price or recovering it from
income tax. The cost of the product is figured on the price of materials and
what I dare charge for my time.

Basically, I pass the cost of materials directly to you. I go the a lumber
yard and buy plywood, other wood products and fasteners for each order. Because
of my limited volume, I don't get any big breaks on the costs of materials. The
same applies to drivers and electronics. I can't justify stocking a pallet of
drivers, so I don't get a break on pricing. This is the main reason that I
don't offer parts kits. By the time you pay for shipping twice, it is cheaper
for you to buy directly from the supplier. The bright side of this is that I
can offer upgraded parts or special finishes for each and every pair of
speakers. I am not selling you product that I have in stock.

Woodworking in general and finishing in particular is very labor intensive.
I have a set dollar amount I try to net on each set of speakers. If you add up
the cost of parts, you can probably deduce what the amount is, but I'll keep
that to myself for now. Ask yourself what your time is worth and then figure
how long it would take you to build a set of speakers with a furniture grade
finish. I think that you will find my speakers are a bargain.

That said, I will require one-half of the total price at project initiation,
which is not refundable. This will cover my costs of materials and parts. The
remainder of the the price is due once the speakers are complete and
immediately prior to shipping.

Shipping

I offer free shipping within North America.

Ok, there is not such thing as free shipping. I include the average cost of
FedEx shipping plus the costs of materials used. For a pair of floor-standers,
I use ~$40 worth of polystyrene beadboard, $10 worth of cardboard and several
hot-glue sticks. It takes me roughly a day's labor to cut the beadboard and
cardboard and to assemble the boxes. You are getting a good deal here.

Shipping is the most exasperating part of the business. My operation is far
too small to have a network of dealers and ship pallet sized loads. I am pretty
much restricted to using package services -- UPS, FedEx et al. We hear the
horror stories of damage and lost caused by these guys. Well, yes, it happens,
but not very often. I have had good luck getting product to my customers.

By the way, your chances of a damaged shipment are in direct proportion to
the population of your metropolitan area. Almost always, shipping damage is
done in the last 50 feet to your house. Careless/lazy drivers will simply kick
the speakers out of their trucks rather than carefully lift them to the ground.
All of my problems have occurred in NYC and L.A. Out here in Arkansas, my
shipments from Parts Express and Madisound arrive pristine.

Shipping is included in the base price of your speakers. Unless we negotiate
something different, shipping will be by FedEx Home. The stand-mount speakers,
being reasonably light in weight, do not seem to have any problems in the FedEx
system. To help assure save passage of the larger floor-standers, I insure each
speaker, not the pair, for $1000 or actual value, whichever is larger. This
"high-value" flag has worked well. All speakers are wrapped in 2" of
polystyrene beadboard and contained in a hand made cardboard box.

Copyright Notice:

Unless noted otherwise, all text, pictures and drawings belong to me and are
protected by U.S. and international copyright laws. You may quote or copy
anything you want for non-commercial, private use, provided that proper
citations are made. You may use plans found here to build speakers for your own
personal use. You may not use information found here for any commercial use
unless you obtain permission from me. Many of the designs presented here
contain proprietary technology that is licensed to me by Martin J. King. If you wish to use one
of these designs for commercial use, you must first obtain a license. Contact
me for a license agreement.

If you have purchased plans, you may build as may speakers as you want so
long as you do not accept any renumeration -- money or barter. If you intend to
sell the finished speakers for profit, including the cost of your labor, you
may build exactly one pair of speakers. You must purchase a set of plans for
each additional pair of speakers you build. You may not give away or sell any
of these plans to a third party.